Plant for building green tyres for vehicle wheels

ABSTRACT

A plant for building different models of green tyres for vehicle wheels, including a plurality of workstations using elementary semi-finished products is described. A first carcass structure of a first model of tyre is built on a first forming support, in a first workstation, the first carcass structure including at least one first carcass ply obtained from a first elementary semi-finished product, and at least one first pair of annular reinforcing inserts. The first forming support is delivered to a bypass device to go beyond at least one second workstation without transiting through it.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. non-provisional divisional patentapplication claiming priority to U.S. patent application Ser. No.15/309,416 filed on Nov. 7, 2016, which, in turn, is a U.S. nationalstage of International Application PCT/IB2015/054615 filed on Jun. 19,2015, which, in turn, claims priority to Italian applicationMI2014A001119 filed on Jun. 20, 2014, the contents of each of which areincorporated herein by reference in their entirety.

SUMMARY OF INVENTION

The present invention relates to a process for building different modelsof green tyres for vehicle wheels. In particular, the present inventionrelates to a process for building different models of green tyres byusing elementary semi-finished products that are different from eachother.

The present invention also relates to a plant for building differentmodels of green tyres for vehicle wheels. Such a plant can be used tocarry out the aforementioned building process.

The production cycles of a tyre comprises, after a building process inwhich the various components of the tyre itself are made and/orassembled in one or more building lines to form a green tyre, a mouldingand vulcanization process to be carried out in a suitable vulcanizationline, the moulding and vulcanization process being suitable for definingthe structure of the tyre according to a desired geometry and treadpattern.

A tyre generally comprises a toroidally ring-shaped carcass structureincluding one or more carcass plies, strengthened with reinforcing cordslying in substantially radial planes (a radial plane contains therotation axis of the tyre). The ends of each carcass ply are fixedlyassociated with at least one metal annular reinforcing structure, knownas bead core, which constitutes the reinforcement at the beads, i.e. atthe radially inner ends of the tyre, having the function of allowing theassembly of the tyre with a corresponding mounting rim. A band ofelastomeric material, called tread band, is arranged in a radially outerposition with respect to the carcass structure, at the end of themoulding and vulcanization steps, a pattern in relief is formed in thesame for the contact with the ground. A reinforcing structure, generallyknown as belt structure, is arranged between the carcass structure andthe tread band. Such a structure usually comprises, in the case of tyresfor automobile, at least two radially overlapping strips made of rubberfabrics provided with reinforcing cords, usually metallic, arrangedparallel to each other in each strip and crossing over with the cords ofthe adjacent strip, preferably symmetrically with respect to the axialmid-plane of the tyre. Preferably, the belt structure also comprises, ina radially outer position thereof, at least on the ends of theunderlying belt strips, also a third layer of textile or metallic cords,arranged circumferentially (at 0 degrees).

Respective sidewalls made of elastomeric material are also applied in anaxially outer position on the side surfaces of the carcass structure.Such sidewalls extend each from one of the side edges of the tread bandup to the respective annular reinforcing structure at the beads.

Finally, in tubeless tyres, a radially inner layer, called liner, isprovided, such an inner layer having characteristics of impermeabilityto ensure the airtight seal of the tyre itself.

The term “elastomeric material” indicates a composition comprising atleast one elastomeric polymer and at least one reinforcing filler.Preferably, such a composition also comprises additives such ascross-linking agents and/or plasticizers. Due to the presence of thecross-linking agents, such a material can be cross-linked throughheating, so as to form the end product.

The term “green tyre” indicates a tyre obtained from the buildingprocess and not yet vulcanized.

The term “elementary semi-finished products” indicates continuouselongated elements made of elastomeric material. Preferably, theaforementioned continuous elongated elements have at least one textileor metallic reinforcing cord inside them. Even more preferably, theaforementioned continuous elongated elements are cut to size so as toform strips of elastomeric material generally called “strip-likeelements”. Generally, such semi-finished products are arranged close toone another, particularly in the case of strip-like elements that areused for example for making carcass plies, belt strips and some types ofreinforcements. Preferably, such a close arrangement occurs side-by-sideat the longest side of the strip-like element. Preferably, such closearrangement occurs on a substantially cylindrical, and/or substantiallytoroidal, and/or substantially flat, deposition surface.

The term “technological flexibility” indicates the possibility of using,for each tyre, elementary semi-finished products that differ from oneother for the type of elastomeric material or the type of textile ormetal reinforcing cord.

The term “productive flexibility” indicates the possibility of making upfor possible temporarily unavailability of production resources, in abuilding process.

The term “structural component” of the tyre indicates any componentsuitably for performing a function in the tyre, or a portion thereof.Such a structural component is selected, for example, among: liner,under-liner, carcass ply(-ies), under-belt insert, belt strips eithercrossed, or of the zero degrees type, attachment sheet for the treadband, tread band, bead core, bead filler, reinforcing inserts made fromtextile, metallic or only elastomeric material, anti-abrasion insert,sidewall inserts.

The term “size” of the tyre indicates the whole of the geometriccharacteristics that characterise a tyre, i.e. at least width of thetread band, height of the sidewalls, fitting diameter.

The term “model” of tyre o indicates the whole of the structuralcharacteristics (like for example single or two-ply structure, radial orwith crossed carcass plies, with or without belt structure, type of beltstructure—crossed belts, zero degrees belts, both crossed and zerodegrees belts—, type of tread band with one or more layers, etc.), andtechnological characteristics (like for example compound of the variousstructural components, materials of the textile or metallic reinforcingcords, type of formation of the reinforcing cords, etc.).

The term “cycle time” of a plant for building tyres indicates the timeperiod that at normal operating speed passes between the completion ofthe building of one green tyre and the completion of the building of asubsequent green tyre.

In some processes for manufacturing tyres developed up to now, the tyresare produced from a limited number of elementary semi-finished productsfed on a toroidal support. The toroidal support is moved, preferablythrough a robotic system, among a plurality of workstations in each ofwhich a particular building step of the tyre is carried out, throughautomated sequences.

International patent application WO 2008/043382, to the same Applicant,describes a tyre building line on which each tyre being processed ismanufactured by assembling structural components thereof in apredetermined sequence. The building line is provided with workstationsarranged one after the other along a production path, each intended toproduce and assemble a structural component of the tyre being processed.In particular, to build a two-ply carcass structure two workstations areused, each of which comprises a carcass structure assembly apparatus fedwith an elementary semi-finished product and a filling insertapplication device. In operation, a toroidal forming support is fed intoa first workstation for making a first carcass ply and depositing afirst pair of bead cores at the assembly apparatus and for depositingrespective filling inserts at the aforementioned application device.Thereafter, the toroidal forming support is fed into a secondworkstation for making a second carcass ply and depositing a furtherpair of bead cores at the respective assembly apparatus and fordepositing respective filling inserts at the respective applicationdevice.

International patent application WO 2011/077236, to the same Applicant,illustrates a tyre building line provided with workstations, eachintended to produce and assemble a structural component of the tyrebeing processed, and in which in order to build the carcass structureand/or the crown structure a plurality of feeding units of elementarysemi-finished products that are different from each other is provided.

The Applicant has verified that the building lines of the type describedin WO 2008/043382 offer low technological flexibility, at most allowingtyres of different size to be built, but not of different model.

In detail, the Applicant has observed that the assembly apparatuses ofthe workstations specifically provided for making the carcass structuresare associated with a same type of elementary semi-finished product.This is due to the fact that, in two-ply carcass structures of a certainmodel of tyre, the respective carcass plies are typically made from thesame elementary semi-finished product.

The Applicant has noted that in order to pass from building a tyre of afirst model to a tyre of a second model, which differs from the first atleast for the type of semi-finished product from which the respectivecarcass plies are made, it is necessary to wait for the completion ofthe carcass structure of the first model of tyre, in order to then beable to “convert” the relative workstations so as to make them suitablefor making the carcass structure of the second model of tyre.Specifically, the conversion of the workstations consists, at least, ofarranging the respective assembly apparatuses for the use of a differentsemi-finished product, suitable for making the carcass plies of thesecond model of tyre.

The Applicant has therefore realised that, in processes of the typedescribed above, once the building of tyres with certain elementarysemi-finished products has started, it is necessary to interruptproduction in order to modify the selected semi-finished products, withconsequent production drawbacks.

The Applicant has also verified that tyre building lines of the typeindicated above also offer a low production flexibility, since, in thecase of failure of a workstation or of unavailability of a relativetransportation device—i.e. a device that operates on the building lineto transfer each of the tyres being processed in sequence from oneworkstation to the next one—it may be necessary to interrupt theproduction.

The Applicant has indeed observed that, in building lines provided forusing the workstations in succession, it is often necessary to passthrough each of the workstations to complete the building of a tyre.

The Applicant has therefore realized that, in such building lines, thefailure of a workstation or of the transportation device associated withit can make it impossible to complete the building of a tyre.

The Applicant has therefore felt the need to improve the productivity ofthe lines for building green tyres in particular, in terms of bothtechnological and operative flexibility.

The Applicant has finally found that providing a process for buildinggreen tyres wherein it is used, in a plant for building tyres, anelementary semi-finished product that is different for each of theworkstations specifically provided for making the carcass structures,making each carcass structure entirely in a respective workstation, atleast in part simultaneously with at least one different carcassstructure made in a different workstation, and wherein it is used aby-pass device that allows the leaving of the tyres being processed fromsaid workstations to be made independent, leads to substantialadvantages in terms of technological and operative flexibility.

The present invention therefore relates, in a first aspect thereof, to aprocess for building different models of green tyres for vehicle wheels,by using elementary semi-finished products, in a building plantcomprising a plurality of workstations.

Preferably, a first carcass structure of a first model of tyre is builton a first forming support in a first workstation.

Preferably, the first carcass structure comprises at least one firstcarcass ply obtained from a first elementary semi-finished product, andat least one first pair of annular reinforcing inserts.

Preferably, at least one second carcass structure of at least one secondmodel of tyre different from said first model of tyre is built on atleast one second forming support, in at least one second workstation.

Preferably, the at least one second carcass structure comprises at leastone first carcass ply obtained from at least one second elementarysemi-finished product different from the first elementary semi-finishedproduct and at least one second pair of annular reinforcing inserts.

Preferably, the building of the first carcass structure and the buildingof the at least one second carcass structure are carried out at least inpart simultaneously with each other.

Preferably, at the end of the building of the first carcass structure,the first forming support is transferred from the first workstation to aworkstation arranged beyond the second workstation, for building atleast one further structural component of the first model of tyre.

Preferably, the aforementioned transfer takes place by delivering thefirst forming support to a by-pass device to go beyond the at least onesecond workstation without transiting through it.

The Applicant believes that such a process makes it possible to have theat least two workstations working independently from each other, thusbeing able to possibly build two different types of green tyres inparallel, without having to wait for the end of the building of thecarcass structure of a first model of tyre (by interrupting theproduction), before being able to move on to the building the carcassstructure of the second model of tyre.

The Applicant thus believes that the process described above makes itpossible to obtain the desired technological and operative flexibilitydue to the fact that it is possible to build in parallel the carcassstructures of at least two different green tyres and to the possibilityof completing each of the aforementioned carcass structures in a singleworkstation.

The Applicant finally believes that in the case of failure of one of theat least two workstations specifically provided for making the carcassstructure it is still possible to complete the building of the tyre,since the carcass structure can be entirely made in just one of the twoworkstations to then be subsequently transferred thus continuing thebuilding of the respective green tyre being processed. Indeed, the firstworkstation is completely independent from the second workstation, alsoregarding the transfer of a tyre being processed, for which the carcassstructure has been completed, downstream of said first and secondworkstations.

In a second aspect thereof, the invention relates to a plant forbuilding different models of green tyres for vehicle wheels by usingelementary semi-finished products.

Preferably, at least one first workstation is provided for building afirst carcass structure on a first forming support.

Preferably, said first workstation comprises a first assembly apparatusconfigured for assembling the first carcass structure.

Preferably, the first assembly apparatus comprises a first feeding unitconfigured for feeding a first elementary semi-finished product onto thefirst forming support.

Preferably, at least one second workstation is provided for building atleast one second carcass structure on at least one second formingsupport.

Preferably, the at least one second workstation comprises at least onesecond assembly apparatus configured for assembling the at least onesecond carcass structure.

Preferably, the at least one second assembly apparatus comprises atleast one second feeding unit configured for feeding a second elementarysemi-finished product, different from the first elementary semi-finishedproduct, onto the at least one second forming support.

Preferably, at least one by-pass device is provided for transporting thefirst forming support from the first workstation to a workstationarranged beyond the second workstation for building at least one furtherstructural component, without transiting through the second workstation.

Preferably, the first workstation and the second workstation aresynchronised with each other so that the first carcass structure and thesecond carcass structure are built at least in part simultaneously.

The present invention, in at least one of the aforementioned aspects,can have at least one of the following preferred characteristics.

Preferably, building a first carcass structure comprises, in sequence:

-   bringing the first forming support to a first carcass structure    assembly apparatus provided in the first workstation;-   building on the first forming support the at least one first carcass    ply obtained from the first elementary semi-finished product and the    at least one first pair of annular reinforcing inserts so as to    associate each annular reinforcing insert with a respective edge of    the at least one first carcass ply obtained from the first    elementary semi-finished product;-   transferring the first forming support to a first filling insert    application device provided in the first workstation;

applying a filling insert on the at least one first carcass ply obtainedfrom the first elementary semi-finished product.

Preferably, building at least one second carcass structure comprises, insequence:

-   bringing the at least one second forming support to at least one    second carcass structure assembly apparatus provided in the at least    one second workstation;-   building on the at least one second forming support the at least one    first carcass ply obtained from the at least one second elementary    semi-finished product and from the at least one second pair of    annular reinforcing inserts so as to associate each annular    reinforcing insert with a respective edge of the at least one first    carcass ply obtained from the at least one second elementary    semi-finished product;-   transferring the at least one second forming support to a second    filling insert application device provided in the at least one    second workstation;-   applying a filling insert on the at least one first carcass ply    obtained from the at least one second elementary semi-finished    product.

More preferably, building a first carcass structure comprises, afterapplying the filling insert on the at least one first carcass plyobtained from the first elementary semi-finished product:

-   bringing the first forming support to the first carcass structure    assembly apparatus;-   building on the at least one first carcass ply obtained from the    first elementary semi-finished product a further carcass ply    obtained from the first elementary semi-finished product.

More preferably, building at least one second carcass structurecomprises, after applying the filling insert on the at least one firstcarcass ply obtained from the at least one second elementarysemi-finished product:

-   bringing the at least one second forming support back to the at    least one second carcass structure assembly apparatus;-   building on the at least one first carcass ply obtained from the at    least one second elementary semi-finished product a further carcass    ply obtained from the at least one second elementary semi-finished    product.

Even more preferably, building a first carcass structure obtained fromthe first semi-finished product comprises, after building the furthercarcass ply obtained from the first elementary semi-finished product:

-   building a third pair of annular reinforcing inserts so as to    associate each annular reinforcing insert of the third pair of    annular reinforcing inserts with a respective radially inner edge of    the further carcass ply obtained from the first elementary    semi-finished product.

Even more preferably, building at least one second carcass structurecomprises, after building the further carcass ply obtained from the atleast one second elementary semi-finished product:

-   building a fourth pair of annular reinforcing inserts so as to    associate each annular reinforcing insert of the fourth pair of    annular reinforcing inserts with a respective radially inner edge of    the further carcass ply obtained from the at least one second    elementary semi-finished product.

Preferably, after building the third pair of annular reinforcing insertsit is foreseen to:

-   transfer the first forming support to the first filling insert    application device;-   apply a filling insert on the further carcass ply obtained from the    first elementary semi-finished product.

Preferably, after building the fourth pair of annular reinforcinginserts it is foreseen to:

-   transfer the at least one second forming support to the at least one    second filling insert application device;-   apply a filling insert on the further carcass ply obtained from the    at least one second elementary semi-finished product.

Preferably, at the end of building the at least one second carcassstructure, the at least one second forming support is transferred to theworkstation for building at least one further structural component ofsaid at least one second model of tyre.

Preferably the at least one further structural component of the firstmodel of tyre or of the second model of tyre comprises a belt structure.

Preferably, prior to building the first carcass structure and the atleast one second carcass structure in the first workstation and in theat least one second workstation, respectively, the first forming supportor the at least one second forming support is transferred to the firstworkstation or to the at least one second workstation depending onwhether the green tyre to be built is of the first model or of the atleast one second model, respectively.

Preferably, the first forming support and the at least one secondforming support are moved within the first workstation and within the atleast one second workstation through respective transportation devices.

Preferably, the first elementary semi-finished product and the secondelementary semi-finished product are strip-like elements.

Preferably, the at least one first carcass ply and further carcass plyobtained from the first elementary semi-finished product, and the atleast one second carcass ply and further carcass ply obtained from theat least one second elementary semi-finished product are built throughside-by-side deposition of a plurality of strip-like elements adjacentto each other at the longer side thereof.

Preferably, the aforementioned plant has a predetermined cycle time andthe actions of building the first carcass structure and the at least onesecond carcass structure are simultaneous for a time comprised betweenabout 60% and about 140% of the aforementioned cycle time.

Preferably, the first workstation further comprises:

-   a first transportation device configured for transporting the first    forming support towards to and away from the first assembly    apparatus.

More preferably, the first workstation further comprises:

-   a first application unit configured for applying annular reinforcing    inserts on the first forming support.

Even more preferably, the first workstation further comprises:

-   a first filling insert application device configured for applying    the first filling insert on the first forming support.

Preferably, the at least one second workstation further comprises:

-   at least one second transportation device configured for    transporting the at least one second forming support towards to and    away from the at least one second assembly apparatus.

More preferably, the at least one second workstation further comprises:

-   at least one second application unit configured for applying annular    reinforcing inserts on the at least one second forming support.

Even more preferably, the at least one second workstation furthercomprises:

-   at least one second filling insert application device configured for    applying at least one second filling insert on the at least one    second forming support.

Preferably, the workstation arranged beyond the second workstation isconfigured to build, on each of the first carcass structure and at leastone second carcass structure, a belt structure of a respective model oftyre.

More preferably, the by-pass device is a translator carriage.

Alternatively, the by-pass device is an anthropomorphic robotic arm.

The provision of a by-pass device of the second workstation allows thetyre being processed in the first workstation to be transferred to theworkstations arranged downstream of the second workstation in a totallyindependent manner from the second workstation, thus increasing theoverall operative flexibility of the plant.

Preferably, the first workstation comprises at least one first waitingunit for temporarily storing the first forming support.

Preferably, the first workstation comprises two first waiting units.

In this way, it is possible to manage the processing partially inparallel of many tyres in the first workstation.

The provision of many waiting units in the first workstation allows manyforming supports to stop simultaneously in such a workstation forbuilding respective carcass structures.

Preferably, a further waiting unit is arranged upstream of the firstworkstation.

The provision of such a further waiting unit makes it possible toincrease the number of tyres being processed in the first workstation.

Preferably, the at least one second workstation comprises at least onesecond waiting unit for temporarily storing the at least one secondforming support.

Preferably, the at least one second workstation comprises two secondwaiting units.

The provision of many waiting units in the at least one secondworkstation allows many forming supports to stop simultaneously in sucha workstation for building respective carcass structures of a differentmodel from those being built in the first workstation.

Preferably, at least one further waiting unit is arranged upstream ofthe at least one second workstation.

Similarly to what has been said in relation to the first workstation,the provision of such a further waiting unit makes it possible toincrease the number of tyres being processed in the at least one secondworkstation.

Preferably, the first and/or the at least one second transportationdevice comprise respective anthropomorphic robotic arms.

Preferably, the first forming support and the at least one secondforming support are toroidal in shape.

Preferably, the first forming support and the at least one secondforming support have a respective radially outer surface having aprofile which substantially coincides with the profile of the radiallyinner surface of the tyre that it is wished to build on that toroidalsupport.

Preferably, there is a further transportation device configured fortransporting the first forming support and at least one second formingsupport towards the first workstation and towards the at least onesecond workstation, respectively.

Said further transportation device feeds the forming supportsselectively to the first workstation or to the at least one secondworkstation depending on the model of tyre that it is wished to build.

Preferably, there is at least one waiting unit configured for receivingthe second forming support carrying the second carcass structure from atransportation device of the second workstation and for allowing thetransportation of the second forming support towards the workstationarranged beyond the second workstation through a transportation deviceassociated therewith.

Preferably, the first assembly apparatus and the at least one secondassembly apparatus build, through the first feeding unit and the atleast one second feeding unit, respectively, each carcass ply belongingto the first carcass structure and to the at least one second carcassstructure, respectively, by arranging close to each other side-by-side aplurality of axially adjacent strip-like elements at the longer sidethereof, respectively.

BREIF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the present invention willbecome clearer from the following detailed description of preferredembodiments thereof, made with reference to the attached drawings.

In such drawings:

FIG. 1 shows a schematic lay-out of an embodiment of a plant forbuilding different models of green tyres for vehicle wheels in which theprocess according to the present invention is carried out; and

FIG. 2 shows a more detailed portion of the plant of FIG. 1.

DETAILED DESCRIPTION

In FIG. 1, reference numeral 9 wholly indicates an embodiment of a plantin which the process for building different models of green tyres forvehicle wheels according to the present invention is carried out.

The plant 9 essentially comprises a building line 2 on which each tyrebeing processed is manufactured by assembling structural components ofthe same tyre in a predetermined sequence, and a vulcanization line 10on which each green tyre coming from the building line 2 is moulded andvulcanized in a respective mould 11.

In the building line 2 the various structural components of the tyre aremade and/or assembled in a plurality of workstations 16, 17, 17′, 18,19, 20 arranged one after the other along a production path, preferablyshaped like a closed ring and shown in the drawing, just as anindication, by the arrows 12, in order to build a green tyre.

The workstations 16, 17, 17′, 18, 19, 20 are provided to work at leastin part simultaneously, each on at least one tyre being processed on arespective forming support to build at least one structural componentthereof on the forming support.

In greater detail, the different structural components used in thebuilding of each tyre are advantageously engaged on a forming support,preferably toroidal in shape. More preferably, said toroidal shape ofthe forming support has a shape such as to substantially match theinternal shape of the tyre to be obtained. This forming support ispreferably of the collapsible tyre or it is intended to be divided intoa plurality of sectors, so as to be able to be easily removed from thetyre at the end of the moulding and vulcanization step.

In the example shown in FIG. 1, various tyres are built at least in partsimultaneously on respective forming supports A, A′. The tyres built onthe forming supports A, A′ are of a different model from each other.

Transportation devices 23, 24, 24′, 26, 27, 28 operates on the buildingline 2 to sequentially transfer each of the tyres being processed on theforming supports A, A′ from one workstation 16, 17, 17′, 18, 19, 20 tothe next workstation, so as to have a sequential building of all of thestructural components of the green tyre and finally transfer the latterto the vulcanization line 10.

Preferably, the transportation devices 23, 24, 24′, 26, 27, 28 compriseone or more anthropomorphic robotic arms each of which is associatedwith at least one of the workstations 16, 17, 17′, 18, 19, 20 and isconfigured to operate on a respective forming support A, A′ to carry outthe sequential transfer of each tyre being processed, as will beexplained more clearly hereafter.

Moreover, in the embodiment illustrated herein, there is a furthertransportation device 22, specifically a robotic arm, which can movealong a guide structure 21 and operates between the building line 2 andthe vulcanization line 10 to pick up a finished tyre from thevulcanization line 10 and transfer it to a service station 15, where thevulcanized tyre is removed from the respective forming support bydisassembling such a support. In the service station 15, the formingsupport is subsequently reassembled to then be transferred, againthrough the robotic arm 22, to a waiting unit 14 from which it will bepicked up for a subsequent use in the building of a new tyre.

A robotic arm 23 carries out the transfer of the forming support fromthe waiting unit 14 to a workstation 16 where the assembly of the firstcomponent is carried out for building the tyre. Such a preliminaryassembly operation can, for example, comprises the coating of the outersurface of the forming support with an airtight thin layer ofelastomeric material, usually called “liner”, as well as the applicationof optional elastomeric compounds close to the regions corresponding tothe beads of the tyre and/or a further coating layer of elastomericmaterial, arranged on the top of the liner.

Preferably, each workstation 16, 17, 17′, 18, 19, 20 is provided with atleast one respective feeding unit configured to feed a specificelementary semi-finished product onto the forming support for making thecorresponding structural component and operating in combination withapplication devices configured for applying the elementary semi-finishedproduct and/or the structural components obtained.

When the assembly of the components in the workstation 16 has beencompleted, the second robotic arm 23 deposits the forming support withthe respective tyre being processed in one of two further waiting units14′, 14′a.

The waiting units 14′, 14′a are each associated with a respectiveworkstation 17, 17′ for building a respective carcass structure of arespective model of tyre. Each workstation 17, 17′ is associated with arespective robotic arm 24, 24′.

Preferably, the waiting units 14′, 14′a are arranged upstream of therespective workstations 17, 17′.

Workstation 17 is arranged upstream of the workstation 17′ in theproduction path 12.

The robotic arms 24, 24′ simultaneously or in succession pick up theforming supports from the respective waiting units 14′, 14′a to transferthem to the workstation 17 or to the workstation 17′, respectively.

When the first carcass structure has been completed in the workstation17, the robotic arm 24 places the forming support with the respectivetyre being processed at a first transfer position 41.

A by-pass device 40 picks up the forming support from the first transferposition 41 to transport it to a second transfer position 42 arrangedclose to a workstation 18 for building a belt structure. The workstation18 is arranged downstream of the workstation 17′. The transfer of theforming support from the workstation 17 to the workstation 18 thus takesplace without transiting through the workstation 17′.

Preferably, the by-pass device is a translator carriage or alternativelyan anthropomorphic robotic arm.

When the carcass structure built in the workstation 17′ is completed,the robotic arm 24′ places the forming support on which theaforementioned carcass structure was formed in a waiting unit 14″. Alsothe waiting unit 14″ is placed close to the aforementioned workstation18.

A robotic arm 26 picks up the forming support which is in the waitingunit 14″ or the forming support which is in the transfer unit 42 tobring it to the workstation 18 for the building of a belt structure.

When the building of the belt structure has been completed, the roboticarm 26 transfers the forming support on which the aforementioned beltstructure has been formed to a workstation 19 for the application of atread band.

In the workstation 19 the forming support carrying the tyre beingprocessed is engaged by a robotic arm 27 with the help of which theapplication of the tread band is carried out. Specifically, the treadband is obtained by winding a continuous elongated element ofelastomeric material in coils arranged consecutively side by side and/orat least partially overlapping until a tread band is obtained having thedesired thickness and shape.

Preferably, the tyre is subsequently transferred to a workstation 20 forthe application of anti-abrasion elements and sidewalls. In theworkstation 20 the forming support is engaged by a robotic arm 28 thatcauses a suitable movement thereof in front of the respective workapparatuses to carry out the application of abrasion resistant elementsin regions corresponding to the beads, as well as the application of thesidewalls, which are preferably obtained by winding a continuouselongated element of elastomeric material to form coils arranged side byside and/or at least partially overlapping.

When this operation has ended, the robotic arm 28 places the built greentyre in an end waiting unit 14″′, before transferring the tyre itself tothe vulcanization line 10.

The vulcanization line 10 advantageously comprises at least one seriesof vulcanization moulds 11 that are mounted on a turntable 30 which canbe set in rotation through a stepped movement so as to allow the mouldsto carry out a closed loop path, along the vulcanization line 10,bringing them in sequence, one after the other, to a loading-unloadingstation 32 of the tyres being processed. Each vulcanization mould 11 issupported by a respective arm 33 of the turntable 30.

With reference to FIG. 2, the workstation 17 for building a firstcarcass structure comprises a first assembly apparatus 51 configured toassemble at least one portion of a first carcass structure of the tyreto be built, for example through the deposition of a plurality ofband-like elements on side and crown portions of the forming support A,to form a carcass ply.

The first assembly apparatus 51 is provided with a first feeding unit 52configured to feed a first elementary semi-finished product, preferablyin the form of band-like elements, such as strip-like elements.

Preferably, the first assembly apparatus 51 builds the carcass ply bybringing together a plurality of first strip-like elements axiallyadjacent to one another at the longer side of the strip-like elements,the first strip-like elements being obtained by cutting to size thefirst elementary semi-finished product that preferably is in the form ofa continuous elongated element reinforced with textile or metal cords.

Similarly, the second workstation 17′ for building a second carcassstructure comprises a second assembly apparatus 51′ configured toassemble at least one portion of a second carcass structure of the tyreto be built, for example through the deposition of a plurality ofband-like elements on side and crown portions of the forming support A′,to form a carcass ply.

The second assembly apparatus 51′ is provided with a second feeding unit52′ configured to feed a second elementary semi-finished product,preferably in the form of band-like elements such as strip-likeelements.

Preferably, also the second assembly apparatus 51′ builds the carcassply by bringing together a plurality of second strip-like elementsaxially adjacent to one another for the longer side of the strip-likeelements, the second strip-like elements being obtained by cutting tosize the second elementary semi-finished product, also preferably in theform of a continuous elongated element reinforced with textile or metalcords.

In particular, the second elementary semi-finished product differs fromthe first elementary semi-finished product, for example for theelastomeric material used to make the elementary semi-finished product,for the type of reinforcing elements inside the elastomeric material andso on.

In this way, it is possible to build in the two workstations 17, 17′carcass structures that are different from each other in order to makedifferent models of green tyres.

A carcass structure is entirely built in the same workstation 17, 17′.In particular, in the case of two-ply carcass structure, both of thecarcass plies made from the same elementary semi-finished product areassembled in the same workstation 17, 17′.

Each assembly apparatus 51, 51′ preferably further comprises anapplication unit configured for applying annular reinforcing inserts 53,53′ intended to form an annular reinforcing insert through thedeposition of a plurality of coils of a first element, preferably in theform of a rubber-coated metal wire, on at least one radially innerportion of the respective forming support A, A′.

Preferably, each of the first and the second workstation 17, 17′ furthercomprises at least one second filling insert application device 54, 54′configured to place a plurality of coils of a second element, preferablyin the form of a continuous elongated element made of elastomericmaterial, on at least one radially inner portion of the respectiveforming support being processed, so as to form a filling insertstructure.

The workstations 17, 17′ are synchronised with each other so that thefirst carcass structure and the second carcass structure are built atleast in part simultaneously.

Each of the workstations 17, 17′ shown in FIG. 2 comprises two innerwaiting units 25 a, 25 b and 25 a′, 25 b′ for temporarily storing aforming support carrying a tyre being processed.

A preferred embodiment of a process for building different models ofgreen tyres for vehicle wheels according to the invention will now bedescribed more in detail.

After the possible first components of the tyre have been assembled inthe workstation 16, the forming support carrying the tyre beingprocessed is transferred to the first workstation 17 or to the secondworkstation 17′ for building a first or a second carcass structure,respectively, depending on whether the green tyre to be built is of afirst model or of a second model, respectively.

In the specific example shown in FIG. 1, the transfer of the formingsupport carrying the tyre being processed out from the workstation 16takes place through the deposition, by the robotic arm 23, of theforming support in the respective waiting unit 14′ or in the waitingunit 14′a arranged upstream of the first workstation 17 and of thesecond workstation 17′, respectively, for building a respective carcassstructure.

From such waiting units 14′, 14′a, the robotic arm 24, 24′ picks up theforming support to start the building of the respective carcassstructure in the workstation 17 (in the specific example illustratedhere, on the forming support A) or in the workstation 17′ (in thespecific example illustrated here, on the forming support A′).

In particular, a first carcass structure of a first model of tyre isbuilt on the forming support A in the first respective workstation 17.

The first carcass structure comprises at least one first carcass plyobtained from the first elementary semi-finished product fed to thefirst workstation 17, and at least one first pair of annular reinforcinginserts.

At least partially in parallel, the process according to the presentinvention comprises building on the forming support A′ a carcassstructure of a second model of tyre, different from the first model, inthe second respective workstation 17′.

The second carcass structure comprises at least one first carcass plyobtained from the second elementary semi-finished product fed to thesecond workstation 17′ and different from the first elementarysemi-finished product, and at least one second pair of annularreinforcing inserts.

The actions of building the carcass structure of the first model of tyreand the carcass structure of the second model of tyre are thereforecarried out at least in part simultaneously.

As specified earlier, the cycle time of a plant for building tyres hereis the time period that at normal operating speed passes between thecompletion of the building of one green tyre and the completion of thebuilding of a subsequent green tyre. In particular, in the case of aplant for building green tyres in which the operations are carried outsequentially, like the plant 9 of FIG. 1, the cycle time is generallydetermined by the building operation having the longest work cycle, inthis specific case by the operation of building a single carcass ply.

Therefore, the first workstation 17 and the second workstation 17′, inwhich even two-ply carcass structures are entirely made, can have a workcycle that can last up to about 300% of the cycle time of the plant 9(because of the building operations of the annular reinforcing insertsand of the filling inserts).

At normal operating speed, considering the time for the forming supportsA and A′ going in and out the respective workstations 17 and 17′, sincethe cycle time substantially coincides with the building of a singlecarcass ply (so that for example the first model of tyre being processedon the forming support A substantially ends the building of the firstcarcass ply when the second model of tyre being processed on the formingsupport A′ enters into the station 17′) the actions for the building ofthe carcass structures on the forming supports A, A′ will besimultaneous preferably for a time comprised between about 60% and about140% of the cycle time of the plant, because of the differences that canexist between different models of different size.

Even more preferably, such actions are carried out simultaneously for atime comprised between about 80% and about 120% of the cycle time of theplant.

In the specific case of building two-ply models, each of the actions forthe building of the first and second carcass structure comprises a firststep of transferring the forming support A, A′ carrying the tyre beingprocessed to the respective carcass structure assembly apparatus 51, 51′provided in the relative workstation 17, 17′.

In such an assembly apparatus 51, 51′ it is carried out the building, onthe forming support, A, A′ of a first carcass ply obtained from thecorresponding elementary semi-finished product and of the respectivefirst or second pair of annular reinforcing inserts so as to associateeach annular reinforcing insert with a respective edge of the firstcarcass ply.

Thereafter, the forming support A, A′ is transferred by the robotic arm24, 24′ to the filling insert application device 54, 54′ provided in thecorresponding workstation 17, 17′, where the application of a fillinginsert on the first carcass ply previously obtained takes place.

The building of the first and second carcass structure preferably alsocomprise, after the application of the filling insert on the firstcarcass ply, bringing the forming support A, A′ back to the respectivecarcass structure assembly apparatus 51, 51′ through the robotic arm 24,24′ for the building on the first carcass ply obtained from therespective elementary semi-finished product of a further carcass plyobtained from the same elementary semi-finished product.

Thereafter, a further pair of annular reinforcing inserts is preferablybuilt so as to associate each annular reinforcing insert of such afurther pair with a respective radially inner edge of the furthercarcass ply obtained from the respective elementary semi-finishedproduct.

Finally, the forming support A, A′ is preferably brought by the roboticarm 24, 24′ back to the respective filling insert application device 54,54′ so as to apply a filling insert on the further carcass ply obtainedfrom the respective elementary semi-finished product.

The management of the passages between the assembly apparatus 51, 51′and the filling insert application device 54, 54′ of the sameworkstation 17, 17′ is supported by the use of the inner waiting units25 a, 25 b, 25 a′, 25 b′ that make it possible to simultaneously manage,in the same building station, the building of three carcass structuresat least partially in parallel.

Specifically, the robotic arm 24, 24′ transfers the forming support A,A′ to the assembly apparatus 51, 51′ where it leaves it for the time inwhich a carcass ply is assembled.

During the assembly time of the carcass ply, the robotic arm 24, 24′ isfree to carry out further operations including, for example:

picking up from the waiting unit 14′, 14′a arranged upstream of theworkstations 17, 17′ a further forming support carrying a tyre beingprocessed to bring it inside the workstation 17, 17′, depositing it atan inner waiting unit 25 a, 25 b, 25 a′, 25 b′;

picking up from another inner waiting unit 25 a, 25 b, 25 a′, 25 b′ aforming support carrying a tyre being processed at which at least onecarcass ply has already been assembled, bringing it to the fillinginsert application device 54, 54′ and supporting such a tyre beingprocessed during the application of the filling insert;

bringing a forming support carrying a tyre being processed to which thefilling insert has been applied back to an inner waiting unit 25 a, 25b, 25 a′, 25 b′;

depositing a forming support carrying a tyre being processed whosecarcass structure has been finished, at the first transfer unit 41 or atthe third waiting unit 14″, respectively.

Moreover, between the assembly of a carcass ply of a first tyre and acarcass ply of a second tyre, the robotic arm 24, 24′ can pick up theforming support A, A′ carrying a first tyre being processed on which theassembly of the carcass ply by the corresponding assembly apparatus 51,51′ has ended, to temporarily deposit it in an inner waiting unit 25 a,25 b, 25 a′, 25 b′, and pick up from the other inner waiting unit 25 a,25 b, 25 a′, 25 b′ a second forming support A, A′ carrying a second tyrethat must be subjected to the assembly of a carcass ply, to bring it tosuch an assembly apparatus 51, 51′.

At the end of the building of the first and of the second carcassstructure, respectively, the corresponding forming support A, A′ istransferred to a workstation in which the building of at least onefurther structural component of the respective model of green tyre iscarried out.

Such a workstation is arranged downstream of the second workstation 17′for building a second carcass structure.

Specifically, in the plant shown in FIG. 1, the workstation arrangeddownstream of the second workstation 17′ to which the forming supportscoming out from the workstations 17, 17′ are transferred is theworkstation 18 for building a belt structure.

The transfer of the forming support A coming out from the workstation 17to the workstation 18 takes place without transiting through theworkstation 17′.

For this purpose, the forming support A is delivered to a by-pass device40, that is, in the specific plant shown in FIG. 1, the robotic arm 24of the workstation 17 places the forming support A at the first transferposition 41.

From such a transfer position 41 the by-pass device 40 picks up theforming support A to transport it to the second transfer position 42arranged near to the workstation 18 for building a belt structure, wheresuch a forming support A can be picked up by the robotic arm 26associated with such a workstation 18 to proceed with the building ofthe further structural components of the tyre.

The transfer of the forming support A′ coming out from the secondworkstation 17′ to the workstation 18 for building a belt structure, onthe other hand, provides for the robotic arm 24′ of the workstation 17′to deposit the forming support A′ in the waiting unit 14″ arranged closeto the workstation 18, from which it can subsequently be picked up bythe robotic arm 26 associated with such a workstation 18 to proceed withthe building of the further structural components of the tyre.

The Applicant finally observed that in the case of malfunctioning of theworkstation 17, for example of the robotic arm 24 and/or of the assemblyapparatus 51, the production can proceed due to the workstation 17′that, through the robotic arm 24′, will arrange each tyre beingprocessed on its own forming support in the waiting unit 14″ once thecarcass structure has been finished. Thereafter, the robotic arm 26, asdescribed above, will allow each tyre being processed to proceed withthe building thereof.

Similarly, in the case of malfunctioning of the workstation 17′, forexample of the robotic arm 24′ and/or of the assembly apparatus 51′, theproduction can proceed due to the workstation 17 that, through therobotic arm 24, will arrange each tyre being processed on its ownforming support in the transfer position 41 once the carcass structurehas been finished. The by-pass device 40 will then bring each tyre tothe transfer position 42. Thereafter, the robotic arm 26, as describedabove, will allow each tyre being processed to proceed with the buildingthereof.

The operative reliability of the plant according to the invention isthus remarkably increased.

The invention claimed is:
 1. A plant for building different models ofgreen tyres for vehicle wheels by using elementary semi-finishedproducts, comprising: at least one first workstation for building afirst carcass structure on a first forming support, said firstworkstation comprising: a first assembly apparatus configured forassembling said first carcass structure, wherein said first assemblyapparatus comprises a first feeding unit configured for feeding a firstelementary semi-finished product onto said first forming support, afirst transportation device configured for transporting said firstforming support towards to and away from said first assembly apparatus,a first application unit configured for applying annular reinforcinginserts on said first forming support, and a first filling insertapplication device configured for applying at least one first fillinginsert on said first forming support; at least one second workstationarranged in a production path downstream of the first workstation forbuilding at least one second carcass structure on at least one secondforming support, said at least one second workstation comprising: atleast one second assembly apparatus configured for assembling said atleast one second carcass structure, wherein said at least one secondassembly apparatus comprises at least one second feeding unit configuredfor feeding a second elementary semi-finished product, wherein thesecond elementary semi-finished product is different from said firstelementary semi-finished product including different elastomericmaterial used to make the first elementary semi-finished product and/ordifferent type of reinforcing elements inside the elastomeric material,onto said at least one second forming support; and at least one bypassdevice for transporting said first forming support from said firstworkstation to a third workstation arranged in the production pathdownstream said second workstation for building at least one furtherstructural component, without transiting through said secondworkstation, wherein said first workstation and said second workstationare synchronised with each other so that said first carcass structureand said second carcass structure are built at least in partsimultaneously.
 2. The plant according to claim 1, wherein said at leastone second workstation further comprises: at least one secondtransportation device configured for transporting said at least onesecond forming support towards to and away from said at least one secondassembly apparatus; at least one second application unit configured forapplying annular reinforcing inserts on said at least one second formingsupport; and at least one second filling insert application deviceconfigured for applying at least one second filling insert on said leastone second forming support.
 3. The plant according to claim 2, whereinsaid third workstation is configured to build, on each of said firstcarcass structure and at least one second carcass structure, a beltstructure of a respective model of tyre.
 4. The plant according to claim3, wherein said at least one bypass device is a translator carriage. 5.The plant according to claim 3, wherein said at least one bypass deviceis an anthropomorphic robotic arm.
 6. The plant according to claim 3,wherein said first workstation comprises at least one first waiting unitfor temporarily storing said first forming support.
 7. The plantaccording to claim 6, wherein said first workstation comprises two firstwaiting units.
 8. The plant according to claim 6, comprising a furtherwaiting unit arranged upstream of said first workstation.
 9. The plantaccording to claim 7, wherein said at least one second workstationcomprises at least one second waiting unit for temporarily storing saidat least one second forming support.
 10. The plant according to claim 9,wherein said at least one second workstation comprises two secondwaiting units.
 11. The plant according to claim 9, comprising at leastone further waiting unit arranged upstream of said at least one secondworkstation.
 12. The plant according to claim 10, wherein said firsttransportation device comprises respective anthropomorphic robotic arms.13. The plant according to claim 12, wherein said first forming supportand at least one second forming support are toroidal in shape.
 14. Theplant according to claim 13, comprising a further transportation deviceconfigured for transporting said first forming support and at least onesecond forming support towards said first workstation and said at leastone second workstation, respectively.
 15. The plant according to claim1, comprising at least one waiting unit configured for receiving saidsecond forming support carrying said second carcass structure from atransportation device of said second workstation and for allowing thetransportation of said second forming support towards said thirdworkstation through a transportation device associated therewith. 16.The plant according to claim 15, wherein said first assembly apparatusand at least one second assembly apparatus build, through said firstfeeding unit and said at least one second feeding unit, respectively,each carcass ply belonging to said first carcass structure and said atleast one second carcass structure, respectively, by arranging close toeach other side-by-side a plurality of axially adjacent strip-likeelements at the longer side thereof, respectively.
 17. The plantaccording to claim 1, wherein said at least one bypass device comprisesa first transfer position in the production path downstream said atleast one first workstation and a second transfer position in theproduction path downstream said at least one second workstation.